FILE - In this June 2, 2012 file photo, Massachusetts Democratic Senate candidate Elizabeth Warren speaks in Springfield, Mass. Massachusetts Sen. Scott Brown has spent weeks fanning questions about Democratic rival Elizabeth Warren's claim of Native American heritage on the campaign trail, while Warren regularly paints Brown as a darling of Wall Street. The rhetoric is sometimes caustic, and all but invisible in the ad war being waged on Massachusetts television sets. (AP Photo/Michael Dwyer, File)